The invention relates to an apparatus for stacking flat workpieces, which are conveyed on a transport cylinder provided with folding tongs, on a stacking table put against the transport cylinder or on stacking arms put against the same which are parallel to each other. The bags or sacks may be provided with a glued bottom, made by the folding-tongs and the apparatus is provided with a means for opening the folding tongs before reaching the stacking table, and with a means for decelerating the workpieces such that the workpieces are set down on the stacking table at a lower speed than the peripheral speed of the transport cylinder.
An apparatus for collecting bags, which were made on a folding-tongs cylinder and are provided with glued bottom, on a stacking table put against the folding-tongs cylinder is, for instance, known f-rom the U.S. Pat. No. 2,087,704. In this known apparatus the bags are released by the folding tongs shortly before reaching the stacking table, so that their leading bottom hits the stacking table almost unretarded at the peripheral speed of the folding-tongs cylinder. When the bags consist of a softer material, the edges hitting the stacking table can therefore get creased or upset.
To prevent a waving, bending or folding of the workpieces set down on the stacking table with their leading edges, an apparatus of the above-mentioned type, which is known from the DE-AS 10 54 818, is provided with tappets having elastic pads mounted on a swivelling frame, which in synchronism with the workpieces being set down are put against the periphery of the folding-tongs cylinder such that they exert a braking torque on the workpieces released by the folding tongs. The braking force exerted by the tappets on the end portion of the workpieces to be decelerated depends, however, on the magnitude of the contract pressure on the folding-tongs cylinder which passes with friction under the decelerated workpiece, so that mutually opposite frictional forces of different magnitudes, which can distort the workpiece, are acting on the two sides of the workpiece, which is disadvantageous in particular, when the same is thin-walled and/or double-walled, as this is the case for instance with bags or sacks.